- Chemoenzymatic synthesis of the calcimimetics (+)-NPS R-568 via asymmetric reductive acylation of ketoxime intermediate
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A practical and efficient procedure for the synthesis of a potent calcimimetic (+)-NPS R-568 was developed. This procedure includes as the key step the asymmetric reductive acylation of a ketoxime intermediate catalyzed by a Pd nanocatalyst and a lipase i
- Han, Kiwon,Kim, Yunwoong,Park, Jaiwook,Kim, Mahn-Joo
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- Beckmann rearrangement of ketoximes promoted by cyanuric chloride and dimethyl sulfoxide under a mild condition
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Synthesis of amides via Beckmann rearrangement of ketoximes promoted by cyanuric chloride (TCT)/DMSO under mild conditions has been reported. Conditions of the Beckmann rearrangement, e.g., solvents, the ratios of TCT/DMSO, and the temperature, were investigated using diphenylmethanone oxime as a substrate. The optimized conditions were adopted to afford fourteen amides with yields ranging from 20% to 99%. A plausible mechanism involving an active dimethyl alkoxysulfonium intermediate was proposed according to the mass spectrometry analysis. To our best knowledge, this is the first case of study on Beckmann rearrangement of ketoximes promoted by TCT/DMSO under a mild condition to afford amides efficiently.
- Ma, Ruonan,Chen, Xueyuan,Xiao, Zhiyin,Natarajan, Mookan,Lu, Chunxin,Jiang, Xiujuan,Zhong, Wei,Liu, Xiaoming
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supporting information
(2021/01/06)
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- Rhodium(III)-Catalyzed Direct C-H Arylation of Various Acyclic Enamides with Arylsilanes
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The stereoselective β-C(sp2)-H arylation of various acyclic enamides with arylsilanes via Rh(III)-catalyzed cross-coupling reaction was illustrated. The methodology was characterized by extraordinary efficacy and stereoselectivity, a wide scope of substrates, good functional group tolerance, and the adoption of environmentally friendly arylsilanes. The utility of this present method was evidenced by the gram-scale synthesis and further elaboration of the product. In addition, Rh(III)-catalyzed C-H activation is considered to be the critical step in the reaction mechanism.
- Li, Xiaolan,Sun, Kai,Shen, Wenjuan,Zhang, Yong,Lu, Ming-Zhu,Luo, Xuzhong,Luo, Haiqing
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supporting information
p. 31 - 36
(2021/01/09)
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- Access to multi-functionalized oxazolines via silver-catalyzed heteroannulation of enamides with sulfoxonium ylides
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Disclosed herein is an efficient Ag-catalyzed [4 + 1] heteroannulation reaction of enamides with α-carbonyl sulfoxonium ylides. The diastereoselective transformation provides a practical access to a diverse range of multi-functionalized oxazoline derivatives. The synthetic utility of the resultant tetra-substituted oxazolines is further demonstrated by a series of useful manipulations into valuable building blocks of pharmaceutical relevance.
- Liu, Rui-Hua,Shan, Qi-Chao,Gao, Ya,Loh, Teck-Peng,Hu, Xu-Hong
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supporting information
p. 1411 - 1414
(2020/10/29)
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- Rhodium(iii)-catalyzed asymmetric [4+1] spiroannulations of: O -pivaloyl oximes with α-diazo compounds
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Chiral RhIII catalysts can catalyze the asymmetric [4+1] spiroannulation of O-pivaloyl oximes with α-diazo homophthalimides under redox-neutral and acid/base-neutral conditions, leading to formation of chiral spirocyclic imines as a result of C-H activation and N-O cleavage. The reaction proceeded with high efficiency and features broad substrate scope, mild reaction conditions, and high to excellent enantioselectivities. This journal is
- Chang, Junbiao,Deng, Wei-Qiao,Kong, Lingheng,Li, Xingwei,Liu, Bingxian,Sun, Lincong,Wang, Fen,Zhao, Yanlian
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supporting information
p. 8268 - 8271
(2021/08/25)
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- Synthesis and SAR Studies of Isoquinoline and Tetrahydroisoquinoline Derivatives as Melatonin Receptor Ligands
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In our constant search for new successors of agomelatine, we report herein a new series of compounds resulting from bioisosteric modulation of the naphthalene ring. The isoquinoline and tetrahydroisoquinoline derivatives were synthesized and pharmacologic
- Caignard, Daniel Henri,Delagrange, Philippe,Ettaoussi, Mohamed,Lebegue, Nicolas,Liberelle, Maxime,Melnyk, Patricia,Rami, Marouane,Vreulz, Brandon,Laversin, Amélie,Yous, Sa?d
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- Chlorotropylium Promoted Conversions of Oximes to Amides and Nitriles
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Chlorotropylium chloride as a catalyst for the transformations of oximes, ketones, and aldehydes to their corresponding amides and nitriles in excellent yields (up to 99 %) and in short reaction times (mostly 10–15 min). Oximes were electrophilically attacked on the hydroxyl oxygen by chlorotropylium. The produced tropylium oxime ethers were the key intermediates, of which the ketoxime ether led to amide through Beckmann rearrangement, and the aldoxime ether led to nitrile by nitrogen base DBU assisted formal dehydration. This chlorotropylium activation protocol offered general, mild, and efficient avenues bifurcately from oximes to both amides and nitriles by one organocatalyst.
- Xu, Jiaxi,Gao, Yu,Li, Zhenjiang,Liu, Jingjing,Guo, Tianfo,Zhang, Lei,Wang, Haixin,Zhang, Zhihao,Guo, Kai
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p. 311 - 315
(2020/01/25)
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- Selective Dehydrogenative Acylation of Enamides with Aldehydes Leading to Valuable β-Ketoenamides
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We have presented a unique example of dehydrogenative acylation of enamides with aldehydes enabled by an earth-abundant iron catalyst. The protocol provides the straightforward access to valuable β-ketoenamides with ample substrate scope and excellent functional group tolerance. Notably, distinct C-H acylation of enamide rather than at N-H moiety site occurs with absolute Z-selectivity was observed. Late-stage modifications of complex molecules and versatile synthetic utility of β-ketoenamides further highlight the practicability of this transformation.
- Liu, Rui-Hua,Shen, Zhen-Yao,Wang, Cong,Loh, Teck-Peng,Hu, Xu-Hong
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supporting information
p. 944 - 949
(2020/02/15)
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- Synthesis of Functionalized Vinylsilanes via Metal-Free Dehydrogenative Silylation of Enamides
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A novel method of metal-free dehydrogenative silylation of enamides has been developed. The desired functionalized vinylsilane products were obtained in moderate to good yield and with high stereoselectivities. This protocol displays good tolerance of various functionalities. Furthermore, the high chemoselectivity of this reaction enables us to introduce different unsaturated C-C moieties to the products. The ease of further derivatization of the products to other useful compounds also demonstrates the highly synthetic utility of the current methodology.
- Chang, Xi-Hao,Wang, Zi-Lu,Zhao, Meng,Yang, Chao,Li, Jie-Jun,Ma, Wei-Wei,Xu, Yun-He
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supporting information
p. 1326 - 1330
(2020/02/13)
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- Access to pyrrolo[2,1-: A] isoindolediones from oxime acetates and ninhydrin via Cu(i)-mediated domino annulations
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A copper-mediated domino condensation reaction of readily accessible oxime acetates with ninhydrin is reported to afford pyrrolo[2,1-a]isoindolediones via new C-C & C-N bond formations. A wide range of oxime acetates were shown to generally participate in the reaction to produce the condensed products in excellent yields. The necessary control experiments were performed and the mechanism is proposed to involve sequentially the formation of iminium radical via Cu-mediated N-O bond cleavage of oxime acetates, addition of the radical to ninhydrin and rearrangement via ring expansion.
- Upare, Atul,Chouhan, Neeraj Kumar,Ramaraju, Andhavaram,Sridhar, Balasubramanian,Bathula, Surendar Reddy
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supporting information
p. 1743 - 1746
(2020/03/17)
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- Copper(0)/PPh3-Mediated Bisheteroannulations of o-Nitroalkynes with Methylketoximes Accessing Pyrazo-Fused Pseudoindoxyls
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A copper(0)/PPh3-mediated cascade bisheteroannulation reaction of o-nitroalkynes with methylketoximes has been developed that provides viable access to a diverse range of pyrazo-fused pseudoindoxyl compounds. Synthetically useful functional groups including sensitive C-I bonds are compatible with this system. Mechanistic studies suggest a reaction cascade involving sequential PPh3-mediated deoxygenative cycloisomerization and copper-catalyzed [3 + 2] pyrazo-annulation.
- Meng, Huanxin,Xu, Zhenhua,Qu, Zhonghua,Huang, Huawen,Deng, Guo-Jun
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supporting information
p. 6117 - 6121
(2020/08/12)
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- Merging alkenyl C-H activation with the ring-opening of 1,2-oxazetidines: Ruthenium-catalyzed aminomethylation of enamides
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1,2-Oxazetidines have been utilized as formaldimine precursors for the direct aminomethylation of enamides under a Ru(ii) species. By merging alkenyl C-H activation with ring-opening of 1,2-oxazetidines, this efficient protocol provides a facile and novel
- Hu, Lu-Min,Hu, Xu-Hong,Li, Song,Ma, Xue-Qing,Shan, Qi-Chao
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supporting information
p. 7969 - 7972
(2020/09/09)
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- SO2F2-Activated Efficient Beckmann Rearrangement of Ketoximes for Accessing Amides and Lactams
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A novel, mild and practical protocol for the efficient activation of the Beckmann rearrangement utilizing the readily available and economical sulfuryl fluoride (SO2F2 gas) has been developed. The substrate scope of the operationally simple methodology has been demonstrated by 37 examples with good to nearly quantitative isolated yields (over 90 % yield in most cases) in a short time, including B(OH)2, COOH, NH2, and OH substituted substrates. A tentative mechanism was proposed involving formation and elimination of key intermediate, sulfonyl ester.
- Zhang, Guofu,Zhao, Yiyong,Xuan, Lidi,Ding, Chengrong
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supporting information
p. 4911 - 4915
(2019/07/31)
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- Rhodium(III)-Catalyzed Annulation of Acetophenone O-Acetyl Oximes with Allenoates through Arene C-H Activation: An Access to Isoquinolines
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Rhodium(III)-catalyzed annulation of acetophenone O-acetyl oximes with allenoates was achieved, affording isoquinolines in good to excellent yields with high regioselectivities under redox-neutral conditions. Allenoates acted as the C2 synthons in the annulation reaction. The present synthetic methodology features good functional group tolerance and avoids metal salts as the external oxidants. The proposed mechanism suggests that the reaction proceeds through arene C-H activation, allene insertion, and C-N coupling.
- Wang, Quannan,Lou, Jiang,Huang, Zilong,Yu, Zhengkun
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p. 2083 - 2092
(2019/02/19)
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- Visible Light-Promoted Beckmann Rearrangements: Separating Sequential Photochemical and Thermal Phenomena in a Continuous Flow Reactor
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The Beckmann rearrangement of oximes to amides typically requires strong acids or highly reactive, hazardous electrophiles and/or elevated temperatures to proceed. A very attractive alternative is the in situ generation of Vilsmeier–Haack reagents, by means of photoredox catalysis, as promoters for the thermal Beckmann rearrangement. Investigation of the reaction parameters for this light-induced method using a one-pot strategy has shown that the reaction is limited by the different temperatures required for each of the two sequential steps. Using a continuous flow reactor, the photochemical and thermal processes have been separated by integrating a flow photoreactor unit at low temperature for the electrophile generation with a second reactor unit, at high temperature, where the rearrangement takes place. This strategy has enabled excellent conversions and yields for a diverse set of oximes, minimizing the formation of side products obtained with the original one-pot method.
- Chen, Yuesu,Cantillo, David,Kappe, C. Oliver
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supporting information
p. 2163 - 2171
(2019/03/14)
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- The ruthenium-catalyzed C-H functionalization of enamides with isocyanates: Easy entry to pyrimidin-4-ones
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Ruthenium-catalyzed heteroannulation between enamides and isocyanates has been realized as a complementary approach to conventional strategies for the synthesis of pyrimidin-4-ones. High step-A nd atom-economy was achieved for the rapid construction of such privileged scaffolds, which are found in a multitude of pharmaceutical compounds. The generality and practicability of this transformation were reflected by the broad scope of substrates with diverse functional groups, large-scale synthesis, and late-stage diversification.
- Shi, Pengfei,Li, Song,Hu, Lu-Min,Wang, Cong,Loh, Teck-Peng,Hu, Xu-Hong
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supporting information
p. 11115 - 11118
(2019/09/20)
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- Redox-Neutral Access to Isoquinolinones via Rhodium(III)-Catalyzed Annulations of O-Pivaloyl Oximes with Ketenes
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A mild and redox-neutral [4 + 2] annulation of O-pivaloyl oximes with ketenes has been realized for synthesis of quaternary-carbon-stereocenter-containing (QCSC) isoquinolinones, where the N-OPiv not only acts as an oxidizing group but also offers coordination saturation to inhibit protonolysis. The reaction mechanism has been studied by DFT calculations.
- Yang, Xifa,Liu, Song,Yu, Songjie,Kong, Lingheng,Lan, Yu,Li, Xingwei
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supporting information
p. 2698 - 2701
(2018/05/22)
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- Scope and mechanism of a true organocatalytic beckmann rearrangement with a boronic acid/perfluoropinacol system under ambient conditions
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Catalytic activation of hydroxyl functionalities is of great interest for the production of pharmaceuticals and commodity chemicals. Here, 2-alkoxycarbonyl- and 2-phenoxycarbonyl-phenylboronic acid were identified as efficient catalysts for the direct and chemoselective activation of oxime N-OH bonds in the Beckmann rearrangement. This classical organic reaction provides a unique approach to prepare functionalized amide products that may be difficult to access using traditional amide coupling between carboxylic acids and amines. Using only 5 mol % of boronic acid catalyst and perfluoropinacol as an additive in a polar solvent mixture, the operationally simple protocol features mild conditions, a broad substrate scope, and a high functional group tolerance. A wide variety of diaryl, aryl-alkyl, heteroaryl-alkyl, and dialkyl oximes react under ambient conditions to afford high yields of amide products. Free alcohols, amides, carboxyesters, and many other functionalities are compatible with the reaction conditions. Investigations of the catalytic cycle revealed a novel boron-induced oxime transesterification providing an acyl oxime intermediate involved in a fully catalytic nonself-propagating Beckmann rearrangement mechanism. The acyl oxime intermediate was prepared independently and was subjected to the reaction conditions. It was found to be self-sufficient; it reacts rapidly, unimolecularly without the need for free oxime. A series of control experiments and 18O labeling studies support a true catalytic pathway involving an ionic transition structure with an active and essential role for the boronyl moiety in both steps of transesterification and rearrangement. According to 11B NMR spectroscopic studies, the additive perfluoropinacol provides a transient, electrophilic boronic ester that is thought to serve as an internal Lewis acid to activate the ortho-carboxyester and accelerate the initial, rate-limiting step of transesterification between the precatalyst and the oxime substrate.
- Mo, Xiaobin,Morgan, Timothy D. R.,Ang, Hwee Ting,Hall, Dennis G.
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supporting information
p. 5264 - 5271
(2018/04/24)
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- Elemental tellurium mediated synthesis of 2-(trifluoromethyl)oxazoles using trifluoroacetic anhydride as reagent
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An elemental tellurium mediated synthesis of 2-(trifluoromethyl)oxazoles from the reaction of acetophenone oxime acetates with trifluoroacetic anhydride has been developed. This new tandem cyclization proceeds in good to excellent yields via a SET reduction followed by a 5-endo-trig pathway. Some of the title compounds showed fungicidal and insecticidal activities.
- Luo, Beibei,Weng, Zhiqiang
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supporting information
p. 10750 - 10753
(2018/09/29)
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- Catalytic Enantio- and Diastereoselective Mannich Addition of TosMIC to Ketimines
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Chiral amines bearing a stereocenter in the α position are ubiquitous compounds with many applications in the pharmaceutical and agrochemical sectors, as well as in catalysis. Catalytic asymmetric Mannich additions represent a valuable method to access such compounds in enantioenriched form. This work reports the first enantio- and diastereoselective addition of commercially available p-toluenesulfonylmethyl isocyanide (TosMIC) to ketimines, affording 2-imidazolines bearing two contiguous stereocenters, one of which is fully-substituted, with high yields and excellent stereocontrol. The reaction, catalyzed by silver oxide and a dihydroquinine-derived N,P-ligand, is broad in scope, operationally simple, and scalable. Derivatization of the products provides enantioenriched vicinal diamines, precursors to NHC ligands and sp3-rich heterocyclic scaffolds. Computations are used to understand catalysis and rationalize stereoselectivity.
- Franchino, Allegra,Chapman, Jack,Funes-Ardoiz, Ignacio,Paton, Robert S.,Dixon, Darren J.
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supporting information
p. 17660 - 17664
(2018/11/10)
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- Catalyst free synthesis of mono- and disubstituted pyrimidines from O-acyl oximes
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Transition-metal or iodine catalyzed transformations of O-acyl oximes to various N-heterocycles are well established. Herein, we report a catalyst free, oxime carboxylate based, three-component condensation method to access mono- and disubstituted pyrimidines. A broad range of substituted pyrimidines were prepared in moderate to excellent yields. Control experiments reveal that in situ generated formamidine is the key intermediate.
- Upare, Atul,Sathyanarayana, Pochampalli,Kore, Ranjith,Sharma, Komal,Bathula, Surendar Reddy
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supporting information
p. 2430 - 2433
(2018/05/23)
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- A su ammonia amide carbamate derivative and application thereof
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The invention belongs to the field of plant bactericide, and relates to a threonyl amine carbamate derivative shown as the general formula (I) and salt capable of being accepted pharmaceutically. Substituent groups R1, R2 and R3 have the definitions given by a specification. The invention further relates to a preparation method of the compound of the general formula (I), a midbody specially developed for preparing the threonyl amine carbamate derivative and an application of the threonyl amine carbamate derivative in plant disease prevention and control. The formula is shown in the specification.
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Paragraph 0055; 0069; 0088
(2017/09/02)
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- Rh(III)- and Zn(II)-Catalyzed Synthesis of Quinazoline N-Oxides via C-H Amidation-Cyclization of Oximes
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Quinazoline N-oxides have been prepared from simple ketoximes and 1,4,2-dioxazol-5-ones via Rh(III)-catalyzed C-H activation-amidation of the ketoximes and subsequent Zn(II)-catalyzed cyclization. The substrate scope and functional group compatibility were examined. The reaction features relay catalysis by Rh(III) and Zn(II).
- Wang, Qiang,Wang, Fen,Yang, Xifa,Zhou, Xukai,Li, Xingwei
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supporting information
p. 6144 - 6147
(2016/12/09)
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- Bifunctional Iminophosphorane Catalyzed Enantioselective Ketimine Phospha-Mannich Reaction
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The enantioselective phospha-Mannich reaction of diethyl phosphite to unactivated N-DPP-protected ketimines catalyzed by a bifunctional iminophosphorane (BIMP) superbase organocatalyst is described. The reaction is applicable to ketimines bearing electron
- Robertson, Gerard P.,Farley, Alistair J. M.,Dixon, Darren J.
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supporting information
p. 21 - 24
(2015/12/26)
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- Enantioselective Hydrosilylation of Imines Catalyzed by Chiral Zinc Acetate Complexes
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A series of zinc acetate complexes with optically pure diphenylethanediamine (DPEDA)-derived ligands have been employed as enantioselective catalyst for the hydrosilylation of various imines. High control of stereoselectivity (up to 97% ee) and excellent yields (up to 96%) were gained for a broad range of N-phosphinoylimines by using (R,R)-N,N′-dibenzyl-1,2-diphenylethane-1,2-diamine. This is the first successful application of an air-stable and environmentally friendly chiral Zn(OAc)2 complex instead of the previously used harmful diethylzinc in the asymmetric reduction of the C=N double bond.
- Bez?ada, Agata,Szewczyk, Marcin,Mlynarski, Jacek
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p. 336 - 342
(2016/01/15)
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- Copper-Catalyzed radical/radical Csp3-H/P-H cross-Coupling: α-Phosphorylation of aryl ketone O-Acetyloximes
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The selective radical/radical cross-coupling of two different organic radicals is a great challenge due to the inherent activity of radicals. In this paper, a copper-catalyzed radical/radical Csp3-H/P-H cross-coupling has been developed. It provides a radical/radical cross-coupling in a selective manner. This work offers a simple way toward β-ketophosphonates by oxidative coupling of aryl ketone o-acetyloximes with phosphine oxides using CuCl as catalyst and PCy3 as ligand in dioxane under N2 atmosphere at 130 C for 5 h, and yields ranging from 47% to 86%. The preliminary mechanistic studies by electron paramagnetic resonance (EPR) showed that, 1) the reduction of ketone o-acetyloximes generates iminium radicals, which could isomerize to α-sp3-carbon radical species; 2)phosphorus radicals were generated from the oxidation of phosphine oxides. Various aryl ketone o-acetyloximes and phosphine oxides were suitable for this transformation.
- Ke, Jie,Tang, Yuliang,Yi, Hong,Li, Yali,Cheng, Yongde,Liu, Chao,Lei, Aiwen
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supporting information
p. 6604 - 6607
(2015/06/08)
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- Synthesis of chiral α-amino tertiary boronic esters by enantioselective hydroboration of α-arylenamides
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The rhodium-catalyzed asymmetric hydroboration of α-arylenamides with BI-DIME as the chiral ligand and (Bpin)2 as the reagent yields for the first time a series of α-amino tertiary boronic esters in good yields and excellent enantioselectivities (up to 99% ee).
- Hu, Naifu,Zhao, Guoqing,Zhang, Yuanyuan,Liu, Xiangqian,Li, Guangyu,Tang, Wenjun
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supporting information
p. 6746 - 6749
(2015/06/16)
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- Cobalt(III)-Catalyzed Dehydrative [4+2] Annulation of Oxime with Alkyne by C-H and N-OH Activation
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Efficient, scalable cobalt-catalyzed redox-neutral [4+2] annulation of readily available oximes and alkyne is reported. The developed synthetic methodology is widely applicable and tolerates various functional groups including heterocycles. A stable CpCoIII neutral complex is employed as the catalyst for this redox-neutral [4+2] annulation reaction, which progresses smoothly by way of a reversible cyclometallation without any external oxidizing agent, and produces only water as the side product.
- Sen, Malay,Kalsi, Deepti,Sundararaju, Basker
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supporting information
p. 15529 - 15533
(2015/11/03)
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- TETRAZOLINONE COMPOUND AND USE THEREOF
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The compound represented by formula (1): wherein R4 and R5 each represents a hydrogen atom, a halogen atom, or a C1-C3 alkyl group; R6 represents a C1-C4 alkyl group, a C3-C6 cycloalkyl group, or the like; R7, R8, and R9 each represents a hydrogen atom, a halogen atom, or the like; R10 represents a C1-C3 alkyl group, or the like; R13 represents a C1-C3 alkyl group, or the like; and Q represents a phenyl group, or the like; has an excellent control effect on pests.
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Paragraph 0844-0845
(2015/11/16)
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- Direct catalytic enantio- and diastereoselective Mannich reaction of isocyanoacetates and ketimines
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A catalytic asymmetric synthesis of imidazolines with a fully substituted β-carbon atom by a Mannich-type addition/cyclization reaction of isocyanoacetate pronucleophiles and N-diphenylphosphinoyl ketimines has been developed. When a combination of a cinchona-derived aminophosphine precatalyst and silver oxide was employed as a binary catalyst system, good reactivity, high diastereoselectivities (up to 99:1 d.r.), and excellent enantioselectivities (up to 99 % ee) were obtained for a range of substrates. Binary catalyst system: A catalytic asymmetric synthesis of imidazolines with a fully substituted β-carbon atom through a Mannich-type addition/cyclization reaction of isocyanoacetate pronucleophiles and N-diphenylphosphinoyl ketimines has been developed. By employing a cinchona-derived aminophosphine precatalyst and silver oxide as a binary catalyst system, good reactivity and high diastereo- and enantioselectivities were obtained.
- Ortin, Irene,Dixon, Darren J.
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supporting information
p. 3462 - 3465
(2014/04/03)
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- Methyl ketone oxime esters as nucleophilic coupling partners in Pd-catalyzed C-H alkylation and application in the synthesis of isoquinolines
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Methyl ketone oxime esters have been found to be excellent coupling partners for C(sp2)-C(sp3) bond formation via Pd-catalyzed aromatic C-H activation. This transformation forms the basis of an approach to regioselectively synthesize substituted isoquinolines via coupling with aryloxime esters. Our mechanistic studies suggested that the reaction proceeded through Pd(II)-catalyzed aromatic C-H activation, tautomerization, and a 1,3-shift of the palladacycle-ligated methyl ketone oxime ester to enable the C-C bond formation by reductive elimination, and intramolecular condensation of an imido-Pd(II) intermediate to form the heterocycle. The aryloxime group not only was used as a directing group for Pd-catalyzed aromatic C-H activation but also functioned as an internal oxidant to allow the reaction to be redox-neutral. Our study illuminated the scope and limitations of this C-H alkylation process, which may serve as the point of departure for developing other C-H functionalization reactions using oxime esters and potentially other carbonyl derivatives as the nucleophilic coupling partners.
- Zhang, Zhi-Wei,Lin, Aijun,Yang, Jiong
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p. 7041 - 7050
(2014/08/18)
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- Bifunctional iminophosphorane organocatalysts for enantioselective synthesis: Application to the ketimine nitro-Mannich reaction
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The design, synthesis, and development of a new class of modular, strongly basic, and tunable bifunctional Bronsted base/H-bond-donor organocatalysts are reported. These catalysts incorporate a triaryliminophosphorane as the Bronsted basic moiety and are readily synthesized via a last step Staudinger reaction of a chiral organoazide and a triarylphosphine. Their application to the first general enantioselective organocatalytic nitro-Mannich reaction of nitromethane to unactivated ketone-derived imines allows the enantioselective construction of β-nitroamines possessing a fully substituted carbon atom. The reaction is amenable to multigram scale-up, and the products are useful for the synthesis of enantiopure 1,2-diamine and α-amino acid derivatives.
- Nunez, Marta G.,Farley, Alistair J. M.,Dixon, Darren J.
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supporting information
p. 16348 - 16351
(2013/12/04)
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- Asymmetric transfer hydrogenation of ketimines using well-defined iron(II)-based precatalysts containing a PNNP ligand
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Well-defined iron(II)-based complexes containing PNNP ligands catalyze a highly enantioselective reduction of N-(diphenylphosphinoyl)- and N-(p-tolylsulphonyl)-ketimines. Under mild conditions and low catalyst loading, the ketimines are successfully reduced to the corresponding amines in enantiomeric excess ranging from 94 to 99%.
- Mikhailine, Alexandre A.,Maishan, Mazharul I.,Morris, Robert H.
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supporting information
p. 4638 - 4641
(2012/10/29)
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- O-acetyl oximes as transformable directing groups for Pd-catalyzed C-H bond functionalization
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[Chemical equation presented] O-Acetyl oxlmes serve as effective directing groups for Pd-catalyzed sp2 and sp3 C-H functionalization reactions. The C-H functionalization products can be subsequently transformed Into ortho- or β-functionalized ketones, alcohols, amines, and heterocycles.
- Neufeldt, Sharon R.,Sanford, Melanie S.
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supporting information; experimental part
p. 532 - 535
(2010/05/02)
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- Rhodium(III)-catalyzed synthesis of isoquinolines from aryl ketone o -acyloxime derivatives and internal alkynes
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A synthetic method of isoquinolines from aryl ketone O-acyloxime derivatives and internal alkynes has been developed using [Cp*RhCl 2]2 - NaOAc as the potential catalyst system. The present transformation is carried out by a redox-neutral sequence of C - H vinylation via ortho-rhodation and C - N bond formation of the putative vinyl rhodium intermediate on the oxime nitrogen, where the N - O bond of oxime derivatives could work as an internal oxidant to maintain the catalytic cycle.
- Too, Pei Chui,Wang, Yi-Feng,Chiba, Shunsuke
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supporting information; experimental part
p. 5688 - 5691
(2011/03/23)
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- Facile and efficient enantioselective strecker reaction of ketimines by chiral sodium phosphate
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A facile and efficient enantioselective Strecker reaction of ketimines catalyzed by a chiral alkali-metal salt has been developed. When 10 mol% BNPNa (BNP=1,1'-binaphthyl-2,2'-diylphosphate) prepared in situ and 10 mol% para-tert-butylortho-adamantylphenol (PBAP) were introduced into the reaction, up to 96% yield and up to 95% ee (ee=enantiomeric excess) were obtained. Both aliphatic and aromatic ketimines, especially sterically bulky cyclic ketimines derived from β-acetonaphthone, α-indanone, and α-tetralone were found suitable for this reaction. On the basis of the experimental results and previous reports, trimethylsilyl cyanide (TMSCN) was indicated to be the real reactive nucleophile despite the existence of PBAP, and a possible working model was proposed to explain the origin of the asymmetric induction. The facile availability of 1,1'-binaphthyl-2,2'-diylphosphoric acid (BNPH) and the simplicity of the procedure are beneficial for practical applications.
- Shen, Ke,Liu, Xiaohua,Cai, Yunfei,Lin, Lili,Feng, Xiaoming
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supporting information; experimental part
p. 6008 - 6014
(2010/02/28)
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- Quinone-sensitized steady-state photolysis of acetophenone oximes under aerobic conditions: Kinetics and product studies
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Oxidation of oximes via photosensitized electron transfer (PET) results in the formation of the corresponding ketones as the major product via oxime radical cations and iminoxyl radicals. The influence of electron-releasing and electron-accepting substituents on these reactions was studied. The observed substituent effect strongly supports formation of iminoxyl radicals from the oximes via an electron transfer-proton transfer sequence rather than direct hydrogen atom abstraction. Correlation of the relative conversion of the oximes with Hammett parameters shows that radical effects dominate for the meta-substituted acetophenone oximes (ρrad/ ρpol = 5.4; r2 = 0.93), whereas the para-substituted oximes are influenced almost equally by radical and ionic effects (ρrad/ ρpol = -1.1; r2 = 0.98). From these data sets we conclude that the follow-up reactions proceed through a number of intermediates with both radical and ionic character. This was confirmed by product studies with the use of an isotopically labeled nucleophile. In addition to the major oxidation product (ketone), a chlorine-containing product was often identified as well. Studies on the formation of this product show that the most likely pathway is either via a direct nucleophilic addition in a complex formed between the oxime radical cation and the chloranil radical anion or via a radical substitution (SH2) mechanism. These studies show that with the increasing use of oximes as drugs and pesticides, intake of these chemicals followed by enzymatic oxidation may result in the formation of a variety of reactive intermediates, which may lead to cell and tissue damage.
- Park, Adriana,Kosareff, Nicole M.,Kim, Jason S.,De Lijser, H. J. Peter
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p. 110 - 118
(2008/02/12)
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